This is a continuation of application Ser. No. 340,929 filed Jan. 20, 1982, and now abandoned.
The present invention relates to a flat type vacuum-fluorescent display matrix with two plates forming the housing walls with at least one of the plates being transparent, transparent conductors provided at least on the inside of the transparent plate and electrodes disposed between the two plates, and to a method of operating same.
It is customary in the construction of vacuum-fluorescent displays to arrange in front of each row of characters containing e.g., 5 times 7 fluorescent segments, one row of sufficiently transparent control grids. In front of these, thin cathode wires are disposed. The corresponding fluorescent segments of all characters are connected with each other by way of conductor leads. By controlling the central grid on the one hand, and the row of identical fluorescent segments on the other hand, it is possible by way of multiplexing, to control the characters of one row differently. The extension (number of characters) of such an arrangement is restricted, and the construction of a matrix composed of several rows of characters would be very expensive.
When constructing e.g., seven-segment displays, a very close arrangement of "character elements" is of no significance, because for reasons of legibility, the figures, letters and symbols must always have a reasonable size. In distinction thereto, for presenting arbitrary patterns, the subdivision (resolution) should be finer when the character shapes to be displayed are more versatile.
Finally, for image reproduction, a comparatively high resolution must be accomplished with the aid of numerous, identical and regularly arranged "picture points". The present state of development in this particular field of technology has been summarized and described in detail in NTZ Vol. 30 (1977), No. 3 by W. Veith: "Flacher Bildschirm"; NTZ Vol. 33 (1980), Nos. 2,3 and 4 by A. Fischer: "Flache Bildschirme" and in Funkschau 52 (1980), Nos. 10 and 11 by G. Troller: "Der flache Fernsehbildschirm". The vacuum fluorescent displays which are frequently used, owing to their brightness and long life expectany, as alphanumeric displays, have a relatively simple construction, but cannot do without control electrodes, such as grids. Liquid-crystal displays are not self-luminous, the service life of electroluminescent panels is still to short, and plasma displays have a complicated construction. German Pat. No. DE-OS 27 42 555 discloses a device which, opposite the large-surface cathode, employs expensive intermediate electrodes for deflecting the electrons, so that five construction elements are arranged above each other, with this again involving the same invenstment as a plurality of conventional gas-discharge type of display panels or screens such as, disclosed in German Pat. No. DE-AS 23 56 036. Also, the display device disclosed in German Pat. No. DE-AS 26 40 632, operating with a wide-fanned electron beam, cannot avoid the hitherto necessary invenstment in control electrodes. Moreover, the complicated controlling methods involve a rather high additional investment.